Overage billing
Overage billing is the practice of charging customers for usage that exceeds a plan's included allotment, typically at a per-unit rate specified on the rate card, applied on top of a base subscription fee or committed volume.
How overage billing fits into a pricing plan
Overage billing is common in hybrid pricing models that combine a flat base fee (covering a fixed included allotment of usage) with a per-unit overage rate for anything consumed beyond that allotment. It gives customers predictable baseline pricing for typical usage while still letting a company recover cost — and margin — from customers whose usage runs well above plan.
What can go wrong
Overage billing is a frequent source of margin leakage when the overage rate on a rate card is not kept current with the underlying vendor cost, or when usage tracking against the included allotment lags real consumption closely enough that a customer's overage goes partly unbilled for a period.
Worked example
A plan includes 1,000,000 tokens per month for a $50.00 base fee, with an overage rate of $6 per 1,000,000 tokens beyond that allotment. A customer consumes 1,350,000 tokens this month.
Invoice with overage
- Overage tokens = 1,350,000 − 1,000,000 = 350,000
- Overage charge = 350,000 tokens × ($6 ÷ 1,000,000) = $2.10
- Total invoice = $50.00 base fee + $2.10 overage = $52.10